diff --git a/dns/client.go b/dns/client.go
index 1d68dc70..1dcaae82 100644
--- a/dns/client.go
+++ b/dns/client.go
@@ -234,6 +234,7 @@ func transform(servers []NameServer) []*nameserver {
 				TLSConfig: &tls.Config{
 					ClientSessionCache: globalSessionCache,
 				},
+				UDPSize: 4096,
 			},
 			Address: s.Addr,
 		})
diff --git a/dns/server.go b/dns/server.go
index 2ece2e97..9db92d78 100644
--- a/dns/server.go
+++ b/dns/server.go
@@ -1,8 +1,10 @@
 package dns
 
 import (
+	"fmt"
 	"net"
 
+	"github.com/Dreamacro/clash/log"
 	D "github.com/miekg/dns"
 )
 
@@ -20,6 +22,11 @@ func (s *Server) ServeDNS(w D.ResponseWriter, r *D.Msg) {
 	msg, err := s.r.Exchange(r)
 
 	if err != nil {
+		if len(r.Question) > 0 {
+			q := r.Question[0]
+			qString := fmt.Sprintf("%s %s %s", q.Name, D.Class(q.Qclass).String(), D.Type(q.Qtype).String())
+			log.Debugln("[DNS Server] Exchange %s failed: %v", qString, err)
+		}
 		D.HandleFailed(w, r)
 		return
 	}